Conventional beverage extractors widely known for application to vending machines and the like are provided with a paper filter feeder that feeds a paper filter for extraction into an extraction chamber where a beverage material, such as a coffee powder, is mixed with hot water to extract a beverage.
A conventional paper filter feeder for beverage extractors is shown in FIG. 1. This paper filter feeder comprises: a rotatable roll core 101 around which a paper filter 100 is wound; a remaining filter detection lever 103, with the center or the front end thereof abutted against the rolled paper filter 100, that is displaced in a direction indicated by an arrow B with a reduction in the amount of the paper filter 100 left; and a microswitch 104 which, when the remaining filter detection lever 103 has reached a position indicated by a chain double-dashed line as a result of a reduction in the amount of the paper filter 100 left, permits a contactor 103A of the remaining filter detection lever 103 to press an actuator 105, whereby switching is performed to output a filter exhaustion signal to a controller (not shown). This paper filter feeder is constructed so that the paper filter 100 is drawn out in a direction indicated by an arrow A through a guide roller 102 and is fed into an extraction chamber (not shown).
In the above construction, upon request of selling, in the extraction chamber, a mixture of the beverage material with hot water is filtered through a paper filter to extract a beverage. After the completion of the extraction, the paper filter 100 is pulled out from the roll core 101 by means of a pair of filter delivery rollers (not shown) and fed in a direction indicated by the arrow A, thereby permitting a fresh surface of the paper filter 100 to be fed into the extraction chamber.
With the progress of selling in this way, a reduction in the amount of the paper filter 100 remaining unused causes displacement of the remaining filter detection lever 103 in a direction indicated by the arrow B. When the amount of the paper filter 100 remaining unused is reduced and the remaining filter detection lever 103 reaches a position indicated by a chain double-dashed line, a contactor 103A of the remaining filter detection lever 103 presses the actuator 105 of the microswitch 104. This leads to switching operation of the microswitch 104 which outputs a filter exhaustion signal to the controller to execute alarm output and the like.
The conventional paper filter feeder for beverage extractors, however, is disadvantageous in that, since whether or not there is still paper filter left is detected by a change in diameter of the paper filter roll, the position of the remaining filter detection lever mounted and the position of the microswitch mounted should be very accurately set so that as soon as the remaining filter detection lever reaches a diameter where no filter paper is left, the microswitch is turned on. For this reason, in order to avoid such a trouble that the exhaustion of the filter paper is not detected in spite of the fact that the paper filter has been used up, the microswitch is set so as to operate while leaving the paper filter, remaining unused, in an amount corresponding to several tens of cups. This poses a problem that a considerable amount of the paper filter is wasted.
In order to solve this problem, Japanese Patent Laid-Open No. 125298/1991 discloses a beverage extractor wherein a detector for detecting the final end of the paper filter is provided before the extraction chamber so that the exhaustion of the paper filter is detected based on the results of the detection provided by the detector. There are two types of paper filters, one of which has a final end fixed to the roll core and the other has a final end not fixed to the roll core. Disadvantageously, the above constructions cannot cope with the former paper filter.
Further, according to the conventional beverage extractors, when a new paper filter is set due to the exhaustion of the paper filter, the setting of the new paper filter is carried out by handwork. In this case, hands of a person who sets the new paper filter are soiled with extraction dregs deposited onto the guide roller and the shaft thereof. Furthermore, when the work space in the beverage extractor is narrow, it is difficult to perform setting of the new paper filter by handwork.